The present invention relates to a brake fluid pressure control system designed to control the pressure of a brake fluid for use, particularly, in a motor vehicle.
Recently, a brake fluid pressure control system employs an external source of fluid pressure. In such a system, fluid pressure is developed in response to brake pedal displacement and applied from the external source to respective wheels. The brake pedal displacement is detected based, for example, on a change in pressure within a master cylinder.
Japanese laid-open patent publication No. 5-65060 discloses a similar brake fluid pressure control system wherein if a primary pressure fed from an external source of fluid pressure is accidentally decreased, an auxiliary pressure is fed from a master cylinder to a wheel cylinder for application of the necessary braking force. To this end, the prior art system includes a fail safe valve which is activated in accident condition to disconnect the wheel cylinder from the external source and in turn, connect the wheel cylinder directly to the master cylinder. In order to inspect the fail safe valve, it is necessary to place the motor vehicle in a maintenance area or a garage.
Accordingly, it is an object of the present invention to provide a brake fluid pressure control system which allows for ready inspection of a fail safe valve and thus, maintains reliability of the fail safe valve.